Cap assembly and secondary battery

ABSTRACT

The disclosure relates to a cap assembly and a secondary battery. The cap assembly includes: a cap plate including a main portion and a convex portion, the main portion including a first surface, a second surface and an electrode lead-out hole; an electrode terminal including an extension portion that extends beyond a hole wall of the electrode lead-out hole and extends in a circumferential direction of the electrode lead-out hole to form a ring structure, and the extension portion is arranged on a side of the first surface away from the second surface; and a sealing ring at least partially disposed between the extension portion and the main portion. The convex portion is disposed on the second surface and around the electrode lead-out hole, and a top surface of the convex portion extends out of the second surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 16/826,228, filed on Mar. 21, 2020, which claims priority to ChinesePatent Application No. 201921066979.7 filed on Jul. 9, 2019, the contentof which are incorporated herein by reference in their entirety.

FIELD

The disclosure relates to the technical field of battery, and inparticular to a cap assembly, a secondary battery and an electricapparatus.

BACKGROUND

Lithium ion secondary batteries have been widely used in the fields ofhybrid vehicles and electric vehicles. This is because it has highenergy, high capacity and high power. The secondary battery includes acap plate, an electrode terminal disposed on the cap plate, a sealingring for sealing the cap plate and the electrode terminal, and a currentcollector connected to the electrode terminal. The cap plate includes anelectrode lead-out hole. The electrode terminal covers the electrodelead-out hole.

SUMMARY

According to embodiments of the disclosure, there is provided a capassembly and a secondary battery. The convex portion of the cap assemblymay increase the strength and rigidity of the section of the mainportion close to the electrode lead-out hole, and reduce the possibilitythat the section is deformed when it is subject to an elastic restoringforce of the sealing ring.

In one aspect, embodiments of the disclosure provide a cap assembly fora secondary battery. The cap assembly includes: a cap plate, anelectrode terminal and a sealing ring. The cap plate includes a mainportion and a convex portion. The main portion includes a first surfaceand a second surface that are disposed opposite to each other in athickness direction of the main portion and an electrode lead-out holepassing through the first surface and the second surface. The electrodeterminal connects to the main portion and covers the electrode lead-outhole. The electrode terminal includes an extension portion that extendsbeyond a hole wall of the electrode lead-out hole in a radial directionof the electrode lead-out hole, the extension portion extends in acircumferential direction of the electrode lead-out hole to form a ringstructure, and the extension portion is arranged on a side of the firstsurface away from the second surface. The sealing ring is at leastpartially disposed between the extension portion and the main portion toseal the electrode lead-out hole. The convex portion is disposed on thesecond surface and around the electrode lead-out hole, and a top surfaceof the convex portion extends out of the second surface.

According to an aspect of embodiments of the disclosure, the convexportion has a thickness of 0.01 mm to 2 mm.

According to an aspect of embodiments of the disclosure, the convexportion includes a ring body disposed around the electrode lead-outhole.

According to an aspect of embodiments of the disclosure, the convexportion includes two or more bosses which are provided at intervals inthe circumferential direction of the electrode lead-out hole.

According to an aspect of embodiments of the disclosure, the top surfaceincludes a planar region and/or a beveled region.

According to an aspect of embodiments of the disclosure, the capassembly further includes a fixing component, the fixing component iswelded to the cap plate and forms a welding zone, and along the radialdirection, the convex portion exceeds the welding zone or the convexportion is flush with an outermost boundary of the welding zone.

According to an aspect of embodiments of the disclosure, the cap plateincludes a recess surrounding the electrode lead-out hole, the fixingcomponent is welded to a side wall of the recess, a section of the mainportion outside of the recess has a maximum thickness D, and there is amaximum thickness H between a bottom wall of the recess and the topsurface, 0.4≤H/D≤0.9.

According to an aspect of embodiments of the disclosure, the cap plateincludes a recess surrounding the electrode lead-out hole, the fixingcomponent is welded to a side wall of the recess, and there is a maximumthickness H between a bottom wall of the recess and the top surface, 0.7mm≤H≤1.5 mm.

According to an aspect of embodiments of the disclosure, the cap plateincludes a recess surrounding the electrode lead-out hole, the fixingcomponent is welded to a side wall of the recess, a portion of thesealing ring between the electrode terminal and the main portion has amaximum compression S, and there is a maximum thickness H between abottom wall of the recess and the top surface, S=kH, and 0<k<1.

According to an aspect of embodiments of the disclosure, along theradial direction, an outer peripheral surface of the sealing ring isarranged outside of an innermost edge of the convex portion.

According to an aspect of embodiments of the disclosure, the secondsurface is smoothly transitioned and connected to an outer surface ofthe convex portion.

According to an aspect of embodiments of the disclosure, the capassembly further includes an insulating component disposed on a side ofthe second surface away from the first surface, the insulating componentincludes a recessed portion in which the convex portion is at leastpartially arranged.

In another aspect, embodiments of the disclosure provide a secondarybattery including: a case including an opening; an electrode assemblydisposed in the case; and a cap assembly according to the aboveembodiments for sealing the opening. The second surface faces theelectrode assembly.

According to another aspect of embodiments of the disclosure, the capassembly further includes an insulating component disposed on a side ofthe second surface away from the first surface, the secondary batteryfurther includes a current collector which includes a main body and anextending portion connected to each other, the main body is arranged ona side of the insulating component away from the second surface, and theextending portion extends into the electrode lead-out hole and isconnected to the electrode terminal; and along an axial direction of theelectrode lead-out hole, there is a first gap between the main body andthe insulating component.

According to another aspect of embodiments of the disclosure, the capassembly further includes an insulating component disposed on a side ofthe second surface away from the first surface, and along an axialdirection of the electrode lead-out hole, there is a second gap betweenthe insulating component and the cap plate.

In another aspect, embodiments of the disclosure provide an electricapparatus including a secondary battery according to the aboveembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical effects of exemplary embodiments ofthe disclosure will be described below with reference to accompanyingdrawings.

FIG. 1 is a structural schematic diagram of a secondary batteryaccording to an embodiment of the disclosure.

FIG. 2 is an exploded structural view of a secondary battery accordingto an embodiment of the disclosure.

FIG. 3 is a structural schematic diagram of a cap plate according to anembodiment of the disclosure.

FIG. 4 is a structural sectional view of a cap assembly according to anembodiment of the disclosure.

FIG. 5 is an enlarged view of a portion A in FIG. 4.

FIG. 6 is an enlarged view of a portion B in FIG. 5.

FIG. 7 is a bottom structural view of a cap plate according to anembodiment of the disclosure.

FIG. 8 is a bottom structural view of a cap plate according to anotherembodiment of the disclosure.

FIG. 9 is a bottom structural view of a cap plate according to anotherembodiment of the disclosure.

FIG. 10 is a partial sectional view of a structure of a cap assemblyaccording to an embodiment of the disclosure.

FIG. 11 is a partial sectional view of a structure of a cap assemblyaccording to another embodiment of the disclosure.

FIG. 12 is a structural sectional view of a sealing ring according to anembodiment of the disclosure.

FIG. 13 is a structural sectional view of a sealing ring according toanother embodiment of the disclosure.

FIG. 14 is a partial exploded structural view of a cap assemblyaccording to an embodiment of the disclosure.

FIG. 15 is a partial sectional view of a structure of a secondarybattery according to an embodiment of the disclosure.

The views are not necessarily plotted in actual proportion in thedrawings.

REFERENCE SIGNS IN THE DRAWINGS

-   -   10 secondary battery;    -   11 case;    -   12 electrode assembly;    -   20 cap assembly;    -   30 cap plate;    -   31 main portion;    -   311 first surface;    -   312 second surface;    -   313 electrode lead-out hole;    -   32 convex portion;    -   321 ring body;    -   322 boss;    -   323 top surface;    -   324 innermost edge;    -   33 recess;    -   331 bottom wall;    -   40 sealing ring;    -   50 terminal assembly;    -   51 fixing component;    -   52 electrode terminal;    -   52 a extension portion;    -   60 insulating component;    -   61 recessed portion;    -   70 current collector;    -   71 main body;    -   80 extending portion;    -   80 first gap;    -   90 second gap;    -   99 welding zone;    -   X radial direction;    -   Y axial direction.

DETAILED DESCRIPTION

Below, embodiments of the disclosure will be further described in detailwith reference to the drawings and embodiments. The detailed descriptionaccording to the embodiments and the accompanying drawings are intendedto exemplary illustrate the principles of the disclosure and are notintended to limit the scope of the disclosure. That is, the disclosureis not limited to the described embodiments.

In the description of the disclosure, it should be noted that, unlessotherwise stated, the meaning of “a plurality” is two or more; theorientation or positional relationship indicated by the terms “upper”,“lower”, “left”, “right”, “inner”, “outer” and the like is merely forthe purpose of describing the disclosure and simplifying thedescription, and is not intended to indicate or imply that the device orcomponent referred to has a particular orientation, is constructed andoperated in a particular orientation, and therefore cannot be understoodto be a limitation of the disclosure. Moreover, the terms “first”,“second”, and the like are configured for descriptive purposes only andare not to be construed as indicating or implying relative importance.

In the description of the disclosure, it should be noted that, unlessotherwise stated, the terms “installation”, “connected to”, and“connected with” are to be understood broadly, and may be, for example,a fixed connection, a disassemble connection, or an integral connection;they can be connected directly or indirectly through an intermediatemedium. The specific meaning of the above terms in the disclosure can beunderstood by the person skilled in the art according to actualcircumstance.

The prior art suffers from at least the following problem: since the capplate and the electrode terminal are hermetically connected by thesealing ring, the compressed portion of the sealing ring produces anelastic restoring force. The elastic restoring force of the sealing ringmay react on the cap plate, so that the portion of the cap plate closeto the electrode lead-out hole may be deformed, which causes a safetyhazard in the use of the secondary battery.

For better understanding of the disclosure, embodiments of thedisclosure will be described below in detail with reference to FIGS. 1to 15.

As shown in FIG. 1 and FIG. 2, a secondary battery 10 according toembodiments of the disclosure includes a case 11, an electrode assembly12 disposed in the case 11 and a cap assembly 20 hermetically connectedto the case 11. According to embodiments of the disclosure, thesecondary battery 10 may be applied in an electric apparatus, such ashybrid vehicle or electric vehicle.

The case 11 according to embodiments of the disclosure is formed in ashape of a rectangular cuboid or in other shapes. The case 11 includesan internal space in which the electrode assembly 12 and electrolyte areaccommodated, and an opening in communication with the internal space.The case 11 may be made of a material such as aluminum, aluminum alloyor plastic.

The electrode assembly 12 according to embodiments of the disclosure mayform a body by stacking a first electrode plate, a second electrodeplate, and a separator between the first electrode plate and the secondelectrode plate together or spirally winding the first electrode plate,the second electrode plate and the separator around a winding axis. Theseparator is an insulator between the first electrode plate and thesecond electrode plate. The electrode assembly 12 according to theembodiment has a flat overall shape with predetermined thickness, heightand width. In the embodiment, the description is made by exemplarilytaking the first electrode plate as a positive electrode plate and thesecond electrode plate as a negative electrode plate. Similarly, inother embodiments, the first electrode plate may be a negative electrodeplate, and the second electrode plate may be a positive electrode plate.Furthermore, a positive active material is coated on a coating region ofthe positive electrode plate, while a negative active material is coatedon a coating region of the negative electrode plate. A plurality ofuncoated regions extending from the coating regions of the body serve astabs. The electrode assembly 12 includes two tabs, i.e., a positive taband a negative tab. The positive tab extends from the coating region ofthe positive electrode plate while the negative tab extends from thecoating region of the negative electrode plate.

As shown in FIG. 2, the cap assembly 20 according to embodiments of thedisclosure includes a cap plate 30 and a terminal assembly 50 connectedto the cap plate 30. The cap plate 30 may cover the opening of the case11 and hermetically connect with the case 11 to enclose the electrodeassembly 12 within the case 11. The cap plate 30 includes an electrodelead-out hole 313. In an embodiment, as shown in FIG. 5, the terminalassembly 50 includes a fixing component 51 and an electrode terminal 52.The electrode terminal 52 is connected to a main portion 31 and coversthe electrode lead-out hole 313. The electrode terminal 52 is connectedto the cap plate 30 through the fixing component 51. The electrodeassembly 12 may be connected to the electrode terminal 52 through acurrent collector. The fixing component 51 includes a hollow cavity inwhich the electrode terminal 52 is accommodated. The hollow cavity ofthe fixing component 51 and the electrode lead-out hole 313 arecorrespondingly disposed in an axial direction Y of the electrodelead-out hole 313.

As shown in FIGS. 3 to 5, the cap plate 30 includes a plate-shaped mainportion 31 and a convex portion 32. The main portion 31 includes a firstsurface 311 and a second surface 312 which are disposed opposite to eachother in its thickness direction. An electrode lead-out hole 313 isprovided in the main portion 31. The electrode lead-out hole 313 passesthrough the first surface 311 and the second surface 312. The thicknessdirection of the main portion 31 is the same as the axial direction Y ofthe electrode lead-out hole 313. The cap plate 30 is hermeticallyconnected to the case 11 through the main portion 31. When the capassembly 20 is applied to a secondary battery, it may be connected tothe case 11 while the second surface 312 of the main portion 31 isadapted to face the electrode assembly 12. Optionally, the cap plate 30is welded to the case 11 through the main portion 31. The convex portion32 is disposed on the second surface 312 of the main portion 31. Theconvex portion 32 is provided around the electrode lead-out hole 313.The convex portion 32 protrudes in the axial direction Y of theelectrode lead-out hole 313 away from the first surface 311. As shown inFIG. 6, a top surface 323 of the convex portion 32 protrudes out of thesecond surface 312. The convex portion 32 has a thickness M of 0.01 mmto 2 mm. The thickness M of the convex portion 32 refers to a maximumvertical distance at which the convex portion 32 protrudes from thesecond surface 312 in the thickness direction. Optionally, the convexportion 32 of the cap plate 30 and the main portion 31 are integrallyformed.

As shown in FIG. 2 and FIG. 5, the cap assembly 20 further includes asealing ring 40. The sealing ring 40 extends in a circumferentialdirection of the electrode lead-out hole 313. A center hole of thesealing ring 40 is disposed corresponding to the electrode lead-out hole313. The electrode terminal 52 includes an extension portion 52 a thatextends beyond a hole wall of the electrode lead-out hole 313 in aradial direction X of the electrode lead-out hole 313. The extensionportion 52 a extends in the circumferential direction of the electrodelead-out hole 313 to form a ring structure. The extension portion 52 ais arranged on a side of the first surface 311 away from the secondsurface 312. When the cap assembly 20 is applied to a secondary battery,the extension portion 52 a is arranged on the side of the main portion31 away from the electrode assembly 12. After the terminal assembly 50is connected and fixed to the cap plate 30, the sealing ring 40 is atleast partially disposed between the extension portion 52 a and the mainportion 31 to seal the electrode lead-out hole 313. The extensionportion 52 a of the electrode terminal 52 and the main portion 31collectively compress a portion of the sealing ring 40 which is disposedbetween the extension portion 52 a and the main portion 31 in the axialdirection Y of the electrode lead-out hole 313. Since the compressedportion of the sealing ring 40 produces an elastic restoring force, theelastic restoring force acts on a section of the main portion 31corresponding to the compressed portion and causes the section to have atrend of deformation in the axial direction Y of the electrode lead-outhole 313. After the convex portion 32 is disposed on the main portion31, the convex portion 32 helps to enhance the deformation resistance ofthe section of the main portion 31 corresponding to the compressedportion, and reduces the possibility of deformation or breakage due tothe elastic restoring force, thereby reducing the possibility of sealfailure.

The cap assembly 20 according to the embodiment of the disclosureincludes a cap plate 30, an electrode terminal 52 and a sealing ring 40.The cap plate 30 includes a main portion 31 and a convex portion 32. Theconvex portion 32 surrounds the electrode lead-out hole 313 disposed inthe main portion 31. The electrode terminal 52 includes an extensionportion 52 a. The portion of the sealing ring 40 disposed between theextension portion 52 a and the main portion 31 produces an elasticrestoring force in the axial direction Y of the electrode lead-out hole313. This elastic restoring force acts on a section of the main portion31 close to the electrode lead-out hole 313. The convex portion 32 mayincrease the strength and rigidity of the section of the main portion 31close to the electrode lead-out hole 313, and reduce the deformationpossibility of the section of the main portion 31 close to the electrodelead-out hole 313 due to a force in the axial direction Y of theelectrode lead-out hole 313, thereby reducing the possibility of sealfailure and improving the safety in use of the secondary battery. Inaddition, since the convex portion 32 may locally increase the strengthand rigidity of the easily deformable region on the main portion 31, thesection of the main portion 31 outside the convex portion 32 may bereduced in size in the thickness direction. Thereby, as compared withthe prior art, the cap plate 30 according to the embodiment includes astructure in which the cap plate 30 is more compact in its thicknessdirection, which is advantageous for increasing the energy density ofthe secondary battery 10.

In one embodiment, the convex portion 32 includes a ring body 321disposed around the electrode lead-out hole 313. The ring body 321extends in the circumferential direction of the electrode lead-out hole313. In one example, as shown in FIG. 7, there is one ring body 321. Thering body 321 and the main portion 31 may be integrally formed by amolding process. In another example, as shown in FIG. 8, there are tworing bodies 321. The two ring bodies 321 have different diameters. Thering body 321 with a smaller diameter among the two ring bodies 321 isdisposed inside the ring body 321 with a larger diameter. The two ringbodies 321 may be arranged coaxially. The number of the ring bodies 321is not limited to one or two, and may be three or more. Three or morering bodies 321 may be arranged in the same way as the two ring bodies321 shown in FIG. 8. The ring body 321 with a smaller diameter isdisposed inside the ring body 321 with a larger diameter. In anotherembodiment, as shown in FIG. 9, the convex portion 32 includes two ormore bosses 322. The two or more bosses 322 are provided at intervals inthe circumferential direction of the electrode lead-out hole 313. Thetwo or more bosses 322 are annularly distributed. In some embodiments,the two or more bosses 322 are evenly distributed along thecircumferential direction of the electrode lead-out holes 313. Thesecond surface 312 of the main portion 31 is smoothly transitioned andconnected to an outer surface of the convex portion 32, thereby thestress concentration between the convex portion 32 and the main portion31 in the transition region may be reduced.

In one embodiment, as shown in FIG. 5 or FIG. 6, the top surface 323 ofthe convex portion 32 may be generally a planar region. In anotherembodiment, as shown in FIG. 10, the top surface 323 of the convexportion 32 is generally a beveled region. The top surface 323 of theconvex portion 32 is an inner side surface that faces an axis of theelectrode lead-out hole 313. An outer edge of the top surface 323 of theconvex portion 32 away from the axis of the electrode lead-out hole 313is higher than its inner edge close to the axis of the electrodelead-out hole 313. As shown in FIG. 11, the top surface 323 of theconvex portion 32 is generally a beveled region. The top surface 323 ofthe convex portion 32 is an outer side surface that is entirely oppositeto the axis of the electrode lead-out hole 313. The outer edge of thetop surface 323 of the convex portion 32 away from the axis of theelectrode lead-out hole 313 is lower than its inner edge close to theaxis of the electrode lead-out hole 313. In another embodiment, the topsurface 323 of the protrusion 32 includes a planar region and a beveledregion. A portion of the top surface 323 may be a planar region, and theremaining portion is a beveled region.

As shown in FIG. 3, the cap plate 30 includes a recess 33 surroundingthe electrode lead-out hole 313. The recess 33 is recessed from thefirst surface 311 toward the second surface 312. The recess 33 includesa bottom wall 331 and a side wall connected to the bottom wall 331. Thebottom wall 331 of the recess 33 is a surface closest to the secondsurface 312. The terminal assembly 50 is at least partially disposedwithin the recess 33 and covers the electrode lead-out hole 313. Thefixing component 51 is in contact with the bottom wall 331 of the recess33. Since the terminal assembly 50 is disposed in the recess 33, thestructural compactness of the cap assembly 20 in the thickness directionis further improved. Thereby, when the cap assembly 20 according to theembodiment is applied to the secondary battery 10, the energy density ofthe secondary battery 10 may be further improved. The fixing component51 is welded to the cap plate 30. As shown in FIG. 6, the fixingcomponent 51 is welded to a portion of the cap plate 30 which forms theside wall of the recess 33, and forms a welding zone 99. The weldingzone 99 has an innermost boundary close to the axis of the electrodelead-out hole 313 and an outermost boundary away from the axis of theelectrode lead-out hole 313. In one example, along the radial directionX of the electrode lead-out hole 313, the convex portion 32 exceeds thewelding zone 99 such that the outermost edge of the convex portion 32exceeds the outermost boundary of the welding zone 99 and is arranged atoutside of the outermost boundary of the welding zone 99. In this way,at one aspect, the convex portion 32 may reduce the possibility that themain portion 31 is melt through. At another aspect, after the weldingzone 99 is formed, the structural strength of the region of the mainportion 31 close to the welding zone 99 is reduced, and it is beneficialto provide the convex portion 32 to increase the structural strength ofthe region. In another example, along the radial direction X of theelectrode lead-out hole 313, the convex portion 32 is flush with theoutermost boundary of the welding zone 99 such that the outermost edgeof the convex portion 32 is flush with the outermost boundary of thewelding zone 99. Since the recess 33 is disposed on the cap plate 30,the region of the main portion 31 corresponding to the recess 33 isrelatively thinned, such that the thickness of the region is relativelyreduced in the thickness direction and thus the section of the mainportion 31 corresponding to the recess 33 forms a cantilever structure.This section is relatively easily deformed when subjected to an externalforce in the axial direction Y of the electrode lead-out hole 313. Theconvex portion 32 connected to the main portion 31 is disposedcorresponding to the recess 33 disposed on the main portion 31, so thatthe convex portion 32 may improve the deformation resistance of thesection of the main portion 31 corresponding to the recess 33, andreduce the possibility that the section is deformed or broken when it issubject to an external force along the axial direction Y of theelectrode lead-out hole 313.

In one embodiment, as shown in FIG. 6, the section of the main portion31 outside of the recess 33 has a maximum thickness D. There is amaximum thickness H between the bottom wall 331 of the recess 33 and thetop surface 323 of the convex portion 32, 0.4≤H/D≤0.9, and 0.7 mm≤H≤1.5mm. In one example, the section of the main portion 31 outside of therecess 33 is a structure with a uniform thickness. The portion of themain portion 31 outside of the recess 33 has a uniform thickness D atrespective positions, i.e., a vertical distance from the first surface311 to the second surface 312 is D. In another example, the main portion31 includes a vent and a fluid inlet. In the axial direction Y of theelectrode lead-out hole 313, an outer contour of a projection of thevent on the main portion 31 forms a first area, an outer contour of aprojection of the fluid inlet on the main portion 31 forms a secondarea, and an outer contour of a projection of the recess 33 on the mainportion 31 forms a third area. An outer contour of a projection of othersections of the main portion 31 outside of the recess 33, the vent andthe liquid inlet forms a fourth area. The first area, the second area,and the third area are each smaller than the fourth area. The thicknessof other sections of the main portion 31 outside of the recess 33, thevent and the liquid inlet is the maximum thickness D of the main portion31.

In another embodiment, There is a maximum thickness H between the bottomwall 331 of the recess 33 and the top surface 323 of the convex portion32, 0.7 mm≤H≤1.5 mm. In the embodiment, there is no proportionalrelationship between the value of the maximum thickness H and the valueof the maximum thickness D of the section of the main portion 31 outsideof the recess 33. The maximum thickness D of the section of the mainportion 31 outside of the recess 33 may be flexibly selected so long asit may satisfy the thickness requirement.

In an embodiment, as shown in FIG. 2 and FIG. 6, a portion of thesealing ring 40 is disposed in the recess 33 to form a first sealingportion, and other portion is disposed outside of the recess 33 to forma second sealing portion. Both the first sealing portion and the secondsealing portion are annular. Along the radial direction X of theelectrode lead-out hole 313, an outer peripheral surface of the sealingring 40 is arranged outside of an innermost edge 324 of the convexportion 32. The outer peripheral surface of the sealing ring 40 isarranged inside an outermost edge of the convex portion 32. The outerperipheral surface of the sealing ring 40 is a surface away from theaxis of the electrode lead-out hole 313 but extending around the axis ofthe electrode lead-out hole 313. Along the axial direction Y of theelectrode lead-out hole 313, a projection of the innermost edge 324 ofthe convex portion 32 is arranged within a projection of the firstsealing portion. After the terminal assembly 50 is connected and fixedto the cap plate 30, the electrode terminal of the terminal assembly 50and the cap plate 30 collectively press the first sealing portion of thesealing ring 40 in the axial direction Y of the electrode lead-out hole313. Since the first sealing portion will produce an elastic restoringforce when being compressed, the elastic restoring force acts on thesection of the main portion 31 corresponding to the recess 33 such thatthe section will have a tendency to deform in the axial direction Y ofthe electrode drawing hole 313. After the convex portion 32 is disposedon the main portion 31, the convex portion 32 helps to enhance thedeformation resistance of the section of the main portion 31corresponding to the recess 33, and reduces the possibility that thesection of the main portion 31 corresponding to the recess 33 isdeformed or broken due to the elastic restoring force of the firstsealing portion and thus reduces the possibility of seal failure. In oneexample, as shown in FIG. 12, the first sealing portion has a maximumcompression S, and there is a maximum thickness H between the bottomwall 331 of the recess 33 and the top surface 323 of the convex portion32, S=kH, and 0<k<1. Optionally, the maximum thickness H between thebottom wall 331 of the recess 33 and the top surface 323 of theprotrusion 32 is in a range of 0.7 mm≤H≤1.5 mm. The larger an amount ofcompression of the first sealing portion, the larger the elasticrestoring force of the first sealing portion. Thus, the maximumthickness between the bottom wall 331 of the recess 33 and the topsurface 323 of the convex portion 32 will be correspondingly increasedsuch that the elastic restoring force may be effectively counteract. Theamount of compression refers to a ratio between a recoverable height ofthe first sealing portion in the axial direction Y when the firstsealing portion returns from the compressed state to the free state anda height of the first sealing portion in the free state along the axialdirection Y. The recoverable height is a difference obtained bysubtracting a height S₂ of the first sealing portion in the compressedstate along the axial direction Y from a height S₁ of the first sealingportion in the free state along the axial direction Y. That is to say,the recoverable height is equal to the difference between S₁ and S₂. Sis equal to the ratio of the recoverable height to S₁.

In another embodiment, the sealing ring 40 is entirely disposed withinthe recess 33 of the main portion 31. After the terminal assembly 50 isconnected and fixed to the cap plate 30, the extension portion 52 a ofthe electrode terminal 52 and the cap plate 30 collectively press theentire sealing ring 40 in the axial direction of the electrode lead-outhole 313 to seal the electrode lead-out hole. Since the sealing ring 40produces an elastic restoring force when being compressed, the elasticrestoring force acts on the section of the main portion 31 correspondingto the recess 33 such that the section will have a tendency to deform inthe axial direction of the electrode drawing hole 313. After the convexportion 32 is disposed on the main portion 31, the convex portion 32helps to enhance the deformation resistance of the section of the mainportion 31 corresponding to the recess 33, and reduces the possibilitythat the section of the main portion 31 corresponding to the recess 33is deformed or broken due to the elastic restoring force of the firstsealing portion and thus reduces the possibility of seal failure. In oneexample, as shown in FIG. 13, the sealing ring 40 has a maximumcompression S, and there is a maximum thickness H between the bottomwall 331 of the recess 33 and the top surface 323 of the convex portion32, S=kH, and 0<k<1. Optionally, the maximum thickness H between thebottom wall 331 of the recess 33 and the top surface 323 of theprotrusion 32 is in a range of 0.7 mm≤H≤1.5 mm. The larger an amount ofcompression of the sealing ring 40 is, the larger the elastic restoringforce of the sealing ring 40 will be. Thus, the maximum thicknessbetween the bottom wall 331 of the recess 33 and the top surface 323 ofthe convex portion 32 will be correspondingly increased such that theelastic restoring force may be effectively counteract. The amount ofcompression refers to a ratio between a recoverable height of thesealing ring 40 in the axial direction Y when the sealing ring 40returns from the compressed state to the free state and a height of thesealing ring 40 in the free state along the axial direction Y. Therecoverable height is a difference obtained by subtracting a height S₂of the sealing ring 40 in the compressed state along the axial directionY from a height S₁ of the sealing ring 40 in the free state along theaxial direction Y. That is to say, the recoverable height is equal tothe difference between S₁ and S₂. S is equal to the ratio of therecoverable height to S₁.

In another embodiment, there is no recess 33 on the main portion 31. Aportion of the sealing ring 40 is disposed between the extension portion52 a of the electrode terminal 52 and the main portion 31 to form afirst sealing portion, and other portion is disposed outside of theextension portion 52 a of the electrode terminal 52 and the main portion31 to form a second sealing portion. After the terminal assembly 50 isconnected and fixed to the cap plate 30, the electrode terminal 52 andthe cap plate 30 collectively compress the first sealing portion of thesealing ring 40 in the axial direction Y of the electrode lead-out hole313. Since the first sealing portion will produce an elastic restoringforce when being compressed, the elastic restoring force acts on themain portion 31 such that the section of the main portion 31corresponding to the first sealing portion will have a tendency todeform in the axial direction Y of the electrode drawing hole 313. Afterthe convex portion 32 is disposed on the main portion 31, the convexportion 32 helps to enhance the deformation resistance of the section ofthe main portion 31 corresponding to the first sealing portion, andreduces the possibility that the section of the main portion 31corresponding to the first sealing portion is deformed or broken due tothe elastic restoring force of the first sealing portion and thusreduces the possibility of seal failure.

In another embodiment, the sealing ring 40 is entirely disposed betweenthe extension portion 52 a of the electrode terminal 52 and the mainportion 31. After the terminal assembly 50 is connected and fixed to thecap plate 30, the extension portion 52 a of the electrode terminal 52and the cap plate 30 collectively compress the sealing ring 40 in theaxial direction Y of the electrode lead-out hole 313. Since the sealingring 40 produces an elastic restoring force when being compressed, theelastic restoring force acts on the main portion 31 such that thesection of the main portion 31 corresponding to the sealing ring 40 willhave a tendency to deform in the axial direction Y of the electrodedrawing hole 313. After the convex portion 32 is disposed on the mainportion 31, the convex portion 32 helps to enhance the deformationresistance of the section of the main portion 31 corresponding to thesealing ring 40, and reduces the possibility that the section of themain portion 31 corresponding to the sealing ring 40 is deformed orbroken due to the elastic restoring force of the sealing ring 40 andthus reduces the possibility of seal failure.

As shown in FIG. 14, the cap assembly 20 further includes an insulatingcomponent 60. The insulating component 60 is disposed on a side of thesecond surface 312 away from the first surface 311. When the capassembly 20 is applied to the secondary battery 10, the insulatingcomponent 60 may isolate the cap plate 30 and the electrode assembly 12.The insulating component 60 and the terminal assembly 50 arerespectively disposed on two sides of the cap plate 30. The insulatingcomponent 60 includes a recessed portion 61 facing a surface of the capplate 30. The convex portion 32 is at least partially arranged in therecessed portion 61. Thereby, in the axial direction Y of the electrodelead-out hole 313, the structural compactness between the insulatingcomponent 60 and the cap plate 30 may be improved, and thus the energydensity of the secondary battery 10 may be improved. In an axialdirection of the electrode lead-out hole 313, a lower surface of theelectrode terminal 52 is higher than a lower surface of the insulatingcomponent 60. In some embodiments, the convex portion 32 is entirelyarranged within the recessed portion 61, and the convex portion 32 andthe recessed portion 61 are shaped to match each other. The number ofthe recessed portions 61 on the insulating component 60 is the same asthe number of the convex portions 32, and the recessed portions 61 andthe convex portions 32 are provided in one-to-one correspondence.

As shown in FIG. 2 and FIG. 15, the secondary battery further includes acurrent collector 70 for connecting to the tabs. The current collector70 includes a main body 71 and an extending portion 72 that areconnected to each other. The main body 71 is arranged on a side of theinsulating component 60 away from the second surface 312. The extendingportion 72 extends into the electrode lead-out hole 313 and is connectedto the electrode terminal 52. Along the axial direction Y of theelectrode lead-out hole 313, there is a first gap 80 between the mainbody 71 and the insulating component 60; and/or along the axialdirection Y of the electrode lead-out hole 313, there is a second gap 90between the insulating component 60 and the cap plate 30. During theprocess of connecting the extension portion 72 of the current collector70 to the electrode terminal 52, the following case will not happen: themain body 71 is interfered by the insulating component 60 such thatthere is poor contact between the extending portion 72 and the electrodeterminal 52 or the connecting region between the extending portion 72and the electrode terminal 52 is subjected to a large axial tensileforce such that the extension portion 72 and the electrode terminal 52will be easily disconnected. Therefore, the connection reliability ofthe extension portion 72 and the electrode terminal 52 is ensured.

An electric apparatus provided by an embodiment of this applicationincludes a secondary battery 10.

Although the disclosure has been described with reference to someembodiments, various modifications may be made to the disclosure andcomponents may be replaced with equivalents without departing from thescope of the disclosure. In particular, the technical features mentionedin the various embodiments can be combined in any manner as long asthere is no structural conflict. The disclosure is not limited to thespecific embodiments disclosed herein, but includes all technicalsolutions falling within the scope of the claims.

What is claimed is:
 1. A cap assembly for a secondary battery,comprising: a cap plate comprising a main portion and a convex portion,wherein the main portion comprises a first surface and a second surfacethat are disposed opposite to each other in a thickness direction of themain portion and an electrode lead-out hole passing through the firstsurface and the second surface; an electrode terminal configured toconnect to the main portion and cover the electrode lead-out hole,wherein the electrode terminal comprises an extension portion that isconfigured to extend beyond a hole wall of the electrode lead-out holein a radial direction of the electrode lead-out hole, the extensionportion is configured to extend in a circumferential direction of theelectrode lead-out hole to form a ring structure, and the extensionportion is arranged on a side of the first surface away from the secondsurface; a fixing component, wherein the electrode terminal is connectedto the cap plate through the fixing component; and a sealing ring whichis at least partially disposed between the extension portion and themain portion to seal the electrode lead-out hole, wherein the convexportion is disposed on the second surface and around the electrodelead-out hole, and a top surface of the convex portion is configured toextend out of the second surface, wherein the fixing component isconfigured to be welded to the cap plate and form a welding zone, andalong the radial direction, the convex portion is configured to exceedthe welding zone or the convex portion is configured to be flush with anoutermost boundary of the welding zone, wherein the fixing componentcomprises a hollow cavity in which the electrode terminal isaccommodated.
 2. The cap assembly according to claim 1, wherein theconvex portion comprises a ring body disposed around the electrodelead-out hole.
 3. The cap assembly according to claim 1, wherein the topsurface comprises a planar region and/or a beveled region.
 4. The capassembly according to claim 1, wherein the cap plate comprises a recesssurrounding the electrode lead-out hole, the fixing component isconfigured to be welded to a side wall of the recess, a section of themain portion outside of the recess has a maximum thickness D, and thereis a maximum thickness H between a bottom wall of the recess and the topsurface, wherein 0.4≤H/D≤0.9.
 5. The cap assembly according to claim 4,wherein 0.7 mm≤H≤1.5 mm.
 6. The cap assembly according to claim 4,wherein a portion of the sealing ring between the electrode terminal andthe main portion has a maximum compression S, and there is a maximumthickness H between a bottom wall of the recess and the top surface,wherein S=kH, and 0<k<1.
 7. The cap assembly according to claim 1,wherein the cap plate comprises a recess surrounding the electrodelead-out hole, the fixing component is configured to be welded to a sidewall of the recess, and there is a maximum thickness H between a bottomwall of the recess and the top surface, wherein 0.7 mm≤H≤1.5 mm.
 8. Thecap assembly according to claim 1, wherein along the radial direction,an outer peripheral surface of the sealing ring is arranged outside ofan innermost edge of the convex portion.
 9. The cap assembly accordingto claim 1, wherein the second surface is smoothly transitioned andconnected to an outer surface of the convex portion.
 10. The capassembly according to claim 1, wherein the cap assembly furthercomprises an insulating component disposed on a side of the secondsurface away from the first surface, the insulating component comprisesa recessed portion in which the convex portion is at least partiallyarranged.
 11. The cap assembly according to claim 10, wherein in anaxial direction of the electrode lead-out hole, a lower surface of theelectrode terminal is higher than a lower surface of the insulatingcomponent.
 12. The cap assembly according to claim 1, wherein the convexportion comprises two or more bosses which are provided at intervals inthe circumferential direction of the electrode lead-out hole.
 13. Thecap assembly according to claim 1, wherein the cap plate comprises arecess surrounding the electrode lead-out hole, the fixing component isconfigured to be welded to a side wall of the recess, a portion of thesealing ring between the electrode terminal and the main portion has amaximum compression S, and there is a maximum thickness H between abottom wall of the recess and the top surface, wherein S=kH, and 0<k<1.14. A secondary battery, comprising: a case comprising an opening; anelectrode assembly disposed in the case; and a cap assembly for sealingthe opening comprising: a cap plate comprising a main portion and aconvex portion, wherein the main portion comprises a first surface and asecond surface that are disposed opposite to each other in a thicknessdirection of the main portion and an electrode lead-out hole passingthrough the first surface and the second surface; an electrode terminalconfigured to connect to the main portion and cover the electrodelead-out hole, wherein the electrode terminal comprises an extensionportion that is configured to extend beyond a hole wall of the electrodelead-out hole in a radial direction of the electrode lead-out hole, theextension portion is configured to extend in a circumferential directionof the electrode lead-out hole to form a ring structure, and theextension portion is arranged on a side of the first surface away fromthe second surface; a fixing component, wherein the electrode terminalis connected to the cap plate through the fixing component; and asealing ring which is at least partially disposed between the extensionportion and the main portion to seal the electrode lead-out hole,wherein the fixing component is configured to be welded to the cap plateand form a welding zone, and along the radial direction, the convexportion is configured to exceed the welding zone or the convex portionis configured to be flush with an outermost boundary of the weldingzone, wherein the fixing component comprises a hollow cavity in whichthe electrode terminal is accommodated, and wherein the convex portionis disposed on the second surface and around the electrode lead-outhole, a top surface of the convex portion is configured to extend out ofthe second surface, and wherein the second surface is configured to facethe electrode assembly.
 15. The secondary battery according to claim 14,wherein the cap assembly further comprises an insulating componentdisposed on a side of the second surface away from the first surface,the secondary battery further comprises a current collector whichcomprises a main body and an extending portion connected to each other,the main body is arranged on a side of the insulating component awayfrom the second surface, and the extending portion is configured toextend into the electrode lead-out hole and be connected to theelectrode terminal; wherein along an axial direction of the electrodelead-out hole, there is a first gap between the main body and theinsulating component.
 16. The secondary battery according to claim 15,wherein the convex portion comprises a ring body disposed around theelectrode lead-out hole, or the convex portion comprises two or morebosses which are provided at intervals in the circumferential directionof the electrode lead-out hole.
 17. The secondary battery according toclaim 14, wherein the cap assembly further comprises an insulatingcomponent disposed on a side of the second surface away from the firstsurface; wherein along an axial direction of the electrode lead-outhole, there is a second gap between the insulating component and the capplate.
 18. An electric apparatus, comprising a secondary battery,wherein the secondary battery comprises: a case comprising an opening;an electrode assembly disposed in the case; and a cap assembly forsealing the opening comprising: a cap plate comprising a main portionand a convex portion, wherein the main portion comprises a first surfaceand a second surface that are disposed opposite to each other in athickness direction of the main portion and an electrode lead-out holepassing through the first surface and the second surface; an electrodeterminal configured to connect to the main portion and cover theelectrode lead-out hole, wherein the electrode terminal comprises anextension portion that is configured to extend beyond a hole wall of theelectrode lead-out hole in a radial direction of the electrode lead-outhole, the extension portion is configured to extend in a circumferentialdirection of the electrode lead-out hole to form a ring structure, andthe extension portion is arranged on a side of the first surface awayfrom the second surface; a fixing component, wherein the electrodeterminal is connected to the cap plate through the fixing component; anda sealing ring which is at least partially disposed between theextension portion and the main portion to seal the electrode lead-outhole, wherein the fixing component is configured to be welded to the capplate and form a welding zone, and along the radial direction, theconvex portion is configured to exceed the welding zone or the convexportion is configured to be flush with an outermost boundary of thewelding zone, wherein the fixing component comprises a hollow cavity inwhich the electrode terminal is accommodated, and wherein the convexportion is disposed on the second surface and around the electrodelead-out hole, a top surface of the convex portion is configured toextend out of the second surface, and wherein the second surface isconfigured to face the electrode assembly.